Previous studies by us have demonstrated that pregnancy related adaptation in maternal metabolism involve a parallel increase in kinetics of energy-providing substrates, i.e. glucose and fatty acids, with increasing demands on maternal (plus fetal) energy requirements. In contrast, changes in maternal protein and nitrogen metabolism are evident early in gestation, even before any significant fetal N accretion. Thus recent data show that there is significant decrease in the rate of urea synthesis and branched chain amino acid transamination early in pregnancy. Since glutamine and alanine are the major carriers in glutamine kinetics and tranfer of N from branched chain amino acids to alanine and glutamine. Normal non-pregnant adults and pregnant women-normal, gestational diabetic women(GDM) and women with growth retarded fetuses (IUGR) will be studied. It s hypothesized that there will be down regulation of glutamine kinetics during normal pregnancy, and that changes in fetal growth, i.e. in GDM and IUGR, will show decompensation in maternal N metabolism.